Power conversion apparatus

ABSTRACT

A power conversion apparatus includes electronic components configuring a power conversion circuit, a cooler for cooling at least part of the electronic components, and a case housing the electronic components and the cooler. The at least part of the electronic components and the cooler are fixed to and integrated in a frame as an internal unit. The internal unit is fixed within the case through the frame. The frame has such a shape that the at least part of the electronic components is surrounded by the frame from four sides.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims the benefit of priority fromearlier Japanese Patent Applications No. 2010-24557 filed Feb. 5, 2010,and No. 2010-244594 filed Oct. 29, 2010, the descriptions of which areincorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a power conversion apparatus in whichelectronic components configuring a power conversion circuit and acooler for cooling at least part of the electronic components are housedin its case.

2. Related Art

An electric vehicle or a hybrid vehicle is equipped with a powerconversion apparatus such as an inverter or a converter to convertsource power into driving power for a drive motor. As shown in FIG. 30,such a power conversion apparatus 9 includes various electroniccomponents including semiconductor modules 921 each incorporatingtherein switching elements, and a capacitor 922. The electroniccomponents constitute a power conversion circuit. For example, refer toJapanese patent Application Laid-Open No. 2009-159767. To prevent thetemperature of the semiconductor modules 921 from increasingexcessively, a cooler 93 is disposed in contact with the semiconductormodules 921.

The power conversion apparatus 9 further includes a control circuitboard 96 on which a control circuit for controlling the semiconductormodules 921 is formed.

The electronic components including the semiconductor modules 921, thecooler 93 and the control circuit board 96 are fixed to a case 94, andsealed within the case 94.

Accordingly, if the case 94 is not rigid enough, the electroniccomponents fixed to the case 94 may vibrate considerably, causing wirebreakage, or failure in the electronic components due to external forceapplied thereto.

When the power conversion apparatus 9 is located in an enginecompartment of a vehicle, the case 94 may expand or contractconsiderably due to abrupt temperature change. In this case, since thecomponents are fixed directly to the case 94, they may fail due tothermal stress applied to them.

The case 94 of the power conversion apparatus 9 is constituted of a iscase body 940, and bottom and top lids 941 and 942. Accordingly, thecase 94 has two large sealing surfaces required to be water-tight.Accordingly, since the case 94 has to be provided with many sealingmembers, the power conversion apparatus 9 is disadvantageous inmanufacturing cost.

In addition, the maintainability of the power conversion apparatus 9 isnot good enough in this case, because both the bottom lid 941 and thetop lid 942 have to be removed for maintenance work. It might bepossible that the case 94 has only one sealing surface, if the case 94is constituted of a bottomed case body and a top lid. However, in thiscase, the maintainability and rigidity of the case 94 may become worse.

Further, since vibration of the electronic components, such as capacitor922, directly fixed to the case 94 can transmit to a vehicle bodythrough the case 94, unpleasant vibration noise may occur in the vehiclecabin. Conversely, since vibration of the engine can transmit to theelectronic components through the case 94, wire breakage or fault mayoccur.

Incidentally, to mount the power conversion apparatus on a vehicle, itis necessary to change its external shape on a vehicle type to vehicletype basis, because the position of connecting means of the powerconversion apparatus for connection with external devices has to beadjusted depending on the shape and structure of a space (enginecompartment, for example) in which the power conversion apparatus isdisposed. Accordingly, the power conversion apparatus of the type inwhich the electronic components and the cooler are directly assembled tothe case needs to be changed in its internal layout. This makes itdifficult to improve the productivity, and prevents reducing themanufacturing cost.

SUMMARY

An embodiment provides a power conversion apparatus which is capable ofreducing an external force applied to its electronic components whileimproving the rigidity of its case, and which is excellent inmaintainability and can be manufactured at low cost.

As an aspect of the embodiment, a power conversion apparatus includes:electronic components configuring a power conversion circuit; a coolerfor cooling at least part of the electronic components; and a casehousing the electronic components and the cooler; wherein the at leastpart of the electronic components and the cooler are fixed to andintegrated in a frame as an internal unit, the internal unit is fixedwithin the case through the frame, and the frame has such a shape thatthe at least part of the electronic components is surrounded by theframe from four sides.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a schematic explanatory sectional view of a power conversionapparatus according to a first embodiment;

FIG. 2 is a plan view of a frame of the power conversion apparatusaccording to the first embodiment;

FIG. 3 is a bottom view of the frame of the power conversion apparatusaccording to the first embodiment;

FIG. 4 is a cross-sectional view of FIG. 2 along the line A-A (or a-a);

FIG. 5 is a cross-sectional view of FIG. 2 along the line B-B;

FIG. 6 is a front view of the frame of the first embodiment;

FIG. 7 is a plan view of the frame of the first embodiment, on which isa stacked body, a terminal block and the like are assembled;

FIG. 8 is a plan view of the frame of the first embodiment, on which abus bar assembly is further assembled;

FIG. 9 is a view of the frame as viewed from the direction of the arrowC of FIG. 8;

FIG. 10 is a cross-sectional view of FIG. 7 along the line D-D;

FIG. 11 is a plan view of the frame of the first embodiment, on which acapacitor is further assembled;

FIG. 12 is a view of the frame as viewed from the direction of the arrowE of FIG. 11;

FIG. 13 is a plan view of the frame of the first embodiment, on which acontrol circuit board is further assembled, that is, a plan view of aninternal unit of the first embodiment;

FIG. 14 is a front view of the internal unit of the first embodiment;

FIG. 15 is a side view of the internal unit of the first embodiment;

FIG. 16 is a plan view of the internal unit housed in a case of thefirst embodiment;

FIG. 17 is a cross-sectional view of FIG. 16 along the line F-F;

FIG. 18 is a cross-sectional view of FIG. 16 along the line G-G;

FIG. 19 is a cross-sectional view of the power conversion apparatusaccording to the first embodiment as viewed along the line G-G of FIG.16;

FIG. 20 is a cross-sectional view of a power conversion apparatusaccording to a second embodiment;

FIG. 21 is a plan view of the power conversion apparatus according tothe second embodiment before a lid body is assembled;

FIG. 22 is a side view of an internal unit of the power conversionapparatus according to the second embodiment;

FIG. 23 is a bottom view of the internal unit of the second embodiment;

FIG. 24 is a front view of a frame of the power conversion apparatusaccording to the second embodiment;

FIG. 25 is a plan view of the frame of the second embodiment;

FIG. 26 is a bottom view of the frame of the second embodiment;

FIG. 27 is a plan view showing a state in which the stacked body isfixed to the frame according to the third embodiment;

FIG. 28 is a view showing a state in which a pressure member is pushedat an end thereof by a pressure jig according to the third embodiment;

FIG. 29 is a partial cross-sectional perspective view of an H-shapedwall section having a rib according to the third embodiment; and

FIG. 30 is a cross-sectional view of a power conversion apparatusaccording to a conventional art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the accompanying drawings, hereinafter is described anembodiment. Throughout the drawings, components identical with orsimilar to each other are given the same numerals for the sake ofomitting unnecessary explanation.

First Embodiment

A power conversion apparatus according to the first embodiment isdescribed with reference to FIGS. 1 to 19.

As shown in FIG. 1, a power conversion apparatus 1 of this embodiment isconstituted of electronic components (semiconductor modules 21, acapacitor 22 and the like) which constitute a power conversion circuit,a cooler 3 for cooling at least part of the electronic components (thesemiconductor modules 21 in this embodiment), and a case 4 housing theelectronic components and the cooler 3.

The semiconductor modules 21 and the cooler 3 are fixed to andintegrated with a frame 5 to constitute an internal unit 10. Theinternal unit 10 is fixed to the case 4, and sealed within the case 4.

As shown in FIGS. 16 to 18, the internal unit 10 is fixed to the case 4through the frame 5. The frame 5 is made of conductive material, andformed in a shape to surround the semiconductor modules 21 constitutingthe internal unit 10 from all four sides. The frame 5 may be a shapedbody of metal such as aluminum or steel, or alloy. Also, the case 4 maybe a shaped body of metal such as aluminum or steel or alloy.

Each of the semiconductor modules 21 incorporates therein switchingelements such as IGBTs (Insulated Gate Bipolar Transistor) or MOSFETs(Metal-Oxide Semiconductor Field-Effect Transistor). The semiconductormodules 21 are each constituted of a main body section 210 in which theswitching elements are resin-molded, main electrode terminals 212 andcontrol terminals 213. The main electrode terminals 212 and the controlterminals 213 extend from the main body section 210 in the oppositedirections. Controlled electric power is inputted to or outputted fromeach of the semiconductor modules 21 through the main electrodeterminals 212. A control current for controlling the switching elementsis inputted to each of the semiconductor modules 212 through the controlterminals 213.

As shown in FIGS. 7 and 10, the cooler 3 includes cooling tubes 31 eachhaving therein a coolant passage. The internal unit 10 incorporatestherein a stacked body 11 in which the cooling tubes 31 and thesemiconductor modules 21 are stacked alternately. Each of thesemiconductor modules 21 is held between the cooling tubes 31 at bothmajor surfaces thereof. Between each adjacent two of the cooling tubes31, two semiconductor modules 21 are disposed.

Note that the number of the semiconductor modules 21 held between thecooling tubes 31 is not limited and is determined depending on theproduct to be manufactured.

As shown in FIG. 7, the cooling tubes 31 extend in their longitudinaldirection (may be referred to as “the lateral direction Y”)perpendicular to the stacking direction X. Each adjacent two of thecooling tubes 31 are joined through a deformable joint tube 32 at theirboth ends. The cooler 3 includes a coolant introduction tube 331 and acoolant discharge tube 332 respectively connected to both ends in thelateral direction Y of the cooling tube 31 located at one end in thestacking direction X of the stacked body 11.

Accordingly, the coolant introduced from the coolant introduction tube331 spreads in the longitudinal direction (lateral direction Y), whilepassing the joint tubes 32 to be distributed to the respective coolingtubes 31. The coolant exchanges heat with the semiconductor modules 21while flowing through the respective cooling tubes 31. The coolanthaving a temperature increased by the heat exchange passes the jointtubes 32 on the downstream side, and is discharged from the coolantdischarge tube 332.

As the coolant, there may be used a natural coolant such as water andammonia, or water mixed with antifreeze such as ethylene glycol, or afluorocarbon coolant such as fluorinert, or a chlorofluorocarbon coolantsuch as HCFC123 and HFC134a, or an alcoholic coolant such as methanoland alcohol, or a ketone coolant such as acetone.

The internal unit 10 includes a pressure member 12 for pressing thestacked body 11 in the stacking direction X. The pressure member 12 isinterposed between an inner part of the frame 5 and one end of thestacked body 11 (this one end being referred to as “rear end”hereinafter) in the stacking direction X. The stacked body 11 issupported by another inner part of the frame 5 at the other end thereof(referred to as “front end” hereinafter) in the stacking direction X.

The pressure member 12 is constituted of a leaf spring which bentsconvexly toward the stacked body 11. Between the pressure member 12 andthe stacked body 11, a flat reinforcing plate 13 is interposed toprevent the pressing force of the pressure member 12 from being locallyapplied to the cooling tube 31 located at the rear end to therebyprevent this cooling tube 31 from being deformed. A support pin 14 isheld between each of both ends of the pressure member 12 in thelongitudinal direction (lateral direction Y) and the frame 5. Thepressure member 12 is supported by the pair of support pins 14 at itsrear side.

The frame 5 includes a front wall section (first wall section) 52 and arear wall section (fourth wall section) 53 located on both sides in thestacking direction X of the stacked body 11, and a pair of side wallsections (second and third wall sections) 54 joining the front and rearwall sections 52 and 53 at both ends thereof. Hence, as shown in FIGS. 2and 3, the frame 5 has a substantially rectangular shape when viewedfrom the direction perpendicular to both the stacking direction X andthe lateral direction Y (referred to as “height direction Z”hereinafter).

The pressure member 12 is disposed between the rear end in the stackingdirection X of the stacked body 11 and the rear wall section 53. Thecoolant introduction tube 331 and the coolant discharge tube 332 projectfrom the front end in the stacking direction of the stacked body 11 andproject forward from the front wall section 52. The coolant introductiontube 331 and the coolant discharge tube 332 may project backward fromthe rear end of the stacked body 11. In this case, for example, thepressure member 12 is disposed between the coolant introduction tube 331and the coolant discharge tube 332 and between the rear end in thestacking direction X of the stacked body 11 and the rear wall section53.

As show in FIGS. 1 to 3 and 19, the frame 5 includes unit fixingsections 51 for fixing the internal unit 10 to the case 4. At least oneunit fixing section 51 is located on the outside of each of a pair ofsupport sections (the inner surface 521 of the front wall section 52 andthe inner surface 531 of the rear wall section 53) in the stackingdirection X at which the frame 5 is applied with the reaction forcetoward the outside in the stacking direction X applied from the stackedbody 11 and the pressure member 11. In this embodiment, two unit fixingsections 51 are located on the outside of the inner surface 521, andanother two unit fixing sections 51 are located on the outside of theinner surface 531.

Each unit fixing section 51 is shaped to project outward from the frame5 and is formed with a through hole. By inserting a bolt 511 into thethrough hole, and screwing the bolt 511 into a threaded hole formed in acorresponding one of unit support sections 41 formed inside the case 4for each of the unit fixing sections 41, the frame 5 can be fixed to thecase 4 to thereby fix the internal unit 10 to the case 4.

As shown in FIGS. 2, 4 and 5, the wall thickness t1 of the front wallsection 52 and the rear wall section 53 is larger than the wallthickness t2 of the side wall section 54. Here, the wall thicknesses t1and t2 are dimensions in the stacking direction X or lateral direction Yat portions to which the cooling tubes 31 are projected in the stackingdirection X or lateral direction Y.

As shown in FIGS. 4 and 10, at least a part of each of the front wallsection 52 and the rear wall section 53 form an H-shaped wall section 55is having a substantially H-shaped cross section. The H-shaped wallsection 55 is constituted of a pair of longitudinal plate sections 551perpendicular to the stacking direction X, and a connecting section 552connecting these longitudinal plate sections 551 together at the centerof the longitudinal plate sections 551.

As shown in FIGS. 2 and 3, at least a part of each of the side wallsections 54 forms an L-shaped wall section having a substantiallyL-shaped cross section. As show in FIG. 5, the L-shaped wall section(side wall sections 54) is constituted of a main wall portion 541 havinga major surface facing the inner surface of the frame 5, and an inwardportion 542 projecting toward the inner side of the frame 5 from one endof the main wall portion 541 in the direction perpendicular to thestacking direction X. In this embodiment, the L-shaped wall section isformed by the whole of the side wall section 54.

As shown in FIGS. 2 and 7, the inward portion 542 of the side wallsection 54 projects more inward in the vicinity of the support pin 14than the other portions.

The frame 5 is open at both sides in the height direction Z. The frame 5is penetrated in the height direction Z. As shown in FIGS. 9 and 10, themain electrode terminals 212 and the control terminals 213 of eachsemiconductor module 21 respectively project to one side (bottom side)of the height direction Z and the other side (top side) of the heightdirection Z. In the present application, the description is madeassuming that the bottom side of the height direction Z corresponds tothe direction of projection of the main electrode terminals 212, and thetop side of the height direction Z corresponds to the direction ofprojection of the control terminals 213. However, this assumption isjust for explanation. Likewise, the words “front”, “rear”, “lateral” arealso just for explanation.

As shown in FIGS. 1 and 13 to 19, the internal unit 10 includes acontrol circuit board 6 on which a control circuit for controlling theswitching elements included in the semiconductor modules 21 is formed.The control terminals 213 of the semiconductor module 21 are connectedto the control circuit board 6. As shown in FIGS. 13 and 14, the unitfixing sections 51 of the frame 5 are located more outward than theouter edge of the control circuit board 6.

As shown in FIGS. 2, 14 and 15, the frame 5 is provided with four boardfixing sections 56 for fixing the control circuit board 6 to theinternal unit 10, which are located more inward than the unit fixingsections 51.

The board fixing sections 56 are constituted of two bosses formed ineach of the front wall section 52 and the rear wall section 53 so as toproject upward in the height direction Z. As shown in FIGS. 13 to 15,each of the board fixing sections 56 is formed with a threaded hole inwhich a screw 561 is inserted to secure the control circuit board 6 tothe frame 5 in four positions.

As shown in FIGS. 14 and 15, the internal unit 10 includes a capacitor22. The frame 5 includes four capacitor fixing sections 57 for fixingthe capacitor 22 to the internal unit 10. As shown in FIGS. 3, 11 and14, the capacitor fixing sections 57 are located more inward than theunit fixing sections 51.

The capacitor fixing sections 57 are constituted of two bosses formed ineach of the front wall section 52 and the rear wall section 53 so as toproject to the opposite side of the board fixing sections 56, that is,downward in the height direction Z. Each of the capacitor fixingsections 57 is formed with a threaded hole in which a bolt 571 isinserted to secure the capacitor 22 to the frame 5 in four positions.

As shown in FIGS. 11 to 15, the internal unit 10 includes a terminalblock 7 on which input/output terminals 71 for input and output ofcontrolled electric power are mounted for making connection between theinput/output terminals 71 and terminals of external devices such as a DCbattery and an electric rotating machine.

The terminal block 7 is fixed to two support arms 543 by bolts 544, thesupport arms 543 being formed in one of the side wall sections 54 so asto project outward.

The input/output terminals 71 include a pair of capacitor terminals 71Pand 71N electrically connected to a pair of electrodes of the capacitor22, and three output terminals 71U, 71V and 71W electrically connectedto the main electrode terminals 212 of the semiconductor modules 21 andto be respectively connected to the electrodes of the U-phase, V-phaseand W-phase of the three-phase electric rotating machine.

The input/output terminals 71 are respectively formed at one ends of busbars which are connected to the capacitor 22 or semiconductor modules 21at the other ends thereof.

Of these bus bars, the ones 70 respectively formed with the outputterminals 71U, 71V and 71W are partially molded with resin to form anintegrated bus bar assembly 72.

As shown in FIGS. 3, 14 and 15, the frame 5 includes bus bar fixingsections 58 for fixing the bus bar assembly 72. In this embodiment, thebus bar fixing sections 58 are formed in three positions. Two of thethree bus bar fixing sections 58 are located at positions closer to theterminal block 7 than to the center of the frame 5.

The internal unit 10 includes almost all electronic componentsconstituting the power conversion circuit. That is, a number ofelectronic components of the power conversion apparatus 1 belong in theinternal unit 10. The electronic components of the power conversionapparatus 1 other than those connected to external components (cablesand the like) are preferably connected to the internal unit 10 directly.Since the electronic components connected to the external components arenot fixed to the internal unit 10, the internal unit 10 is not necessaryto be modified depending on the vehicle type.

As shown in FIG. 1, the case 4 is constituted of a case body 40 which isopen upward, and a lid body 400 dosing the opening of the case body 40.The unit support sections 41 are formed integrally with the case body40.

The case body 40 is provided with flange sections 42 around the outerperiphery of the opening. Also, the lid body 400 is provided with flangesections 420 around the outer periphery thereof. The case body 40 andthe lid body 400 are joined together with a seal member (not shown)interposed between their flange sections 42 and 420 by bolts 431 andnuts 432. Accordingly, the internal unit 10 is sealed in the case 4.

As shown in FIGS. 16 and 19, each of the coolant introduction tube 331and the coolant discharge tube 332 is connected to the stacked body 11(see FIG. 7) so as to partially protrude from the case 4. Each of thecoolant introduction tube 331 and the coolant discharge tube 332 isprovided with an annular packing 333 at its outer periphery. As shown inFIG. 16, the case body 40 is formed with two recesses (not shown)through which the coolant introduction tube 331 and the coolantdischarge tube 332 pass, respectively. Each of the annular packings 333is held between the case body 40 and the lid body 400 in the state ofbeing fitted to the coolant introduction tube 331 or coolant dischargetube 332 at one of the recesses. Accordingly, the case 4 can behermetically sealed allowing the coolant introduction tube 331 and thecoolant discharge tube 332 to protrude outward from the case 4.

The case 4 is further formed with through holes as passages of electricwires and spaces for installing connectors for connection of theelectronic components and the control circuit board 6 with externaldevices. These through holes are provided with seal members to ensurewater tightness of the case 4.

To assemble the power conversion apparatus 1 having the above-describedstructure, the internal unit 10 is assembled first as shown in FIGS. 13to 15. Next, the internal unit 10 is accommodated and fixed in the casebody 40 as shown in FIGS. 16 to 18. Finally, the internal unit 10 issealed in the case 4 by joining the lid body 400 to the case body 40 asshown in FIGS. 1 and 19.

To assemble the internal unit 10, the frame 5 shown in FIGS. 2 to 6 isprepared.

Next, the stacked body 11 in which the semiconductor modules 21 and thecooling tubes 31 are stacked alternately is disposed inside the frame 5as shown in FIGS. 7 and 10. Incidentally, the cooling tubes 31 arecoupled together through the joint tubes 32, and the cooler 3 includingthe coolant introduction tube 331 and the coolant discharge tube 332connected thereto is assembled before the above step. When the stackedbody 11 is disposed inside the frame 5, the coolant introduction tube331 and the coolant discharge tube 332 are respectively placed onconcave portions 522 formed in the frame (see FIGS. 2 and 6).

The pressure member 12 is disposed between the rear end of the stackedbody 11 and the rear wall section 53.

Subsequently, the pressure member 12 is pushed forward at around bothends thereof by pressure jigs while being elastically deformed in thestacking direction X in order to compress the stacked body 11. When thepressure member 12 is deformed by a predetermined amount, thecolumn-shaped support pins 14 are inserted between the rear wall section53 of the frame 5 and each end of the pressure member 12. Thereafter,the pressure jig is pulled away from the pressure member 12 while beingmoved backward in order to bring the pair of support pins 14 to thestate of being held between the pressure member 12 and the rear wallsection 53. This state is also a state in which the stacked body 11 iscompressed in the stacking direction by a predetermined pressure due toan urging force applied from the pressure member 12.

Next, the terminal block 7 is fixed to the support arms 543 of the frame5 by the bolts 544 as shown in FIGS. 7 to 9.

Next, the resin-molded bus bar assembly 72 is fixed to the frame 5, andthe bus bars 70 are welded to the main electrode terminals 212 of thesemiconductor modules 21. Further, the input/output terminals 71U, 71Vand 71W formed in the bus bars 70 are placed on the terminal block 7.The bus bar assembly 72 is fixed to bus bar fixing sections 58 formed atthree positions in the frame 5 by bolts 581.

Thereafter, bus bars 700 for connection between the semiconductormodules 21 and the capacitor 22 are welded to the main electrodeterminals 212 of the semiconductor modules 21, and fixed to the bus barassembly 72 by bolts 701.

Next, as shown in FIGS. 11 and 12, the capacitor 22 is fixed to thelower side of the frame 5. More precisely, the capacitor 22 is securedto the capacitor fixing sections 57 provided in the frame 5 by the bolts571, and the pair of capacitor terminals 71P and 71N are disposed on theterminal block 7.

Next, as shown in FIGS. 13 to 15, the control circuit board 6 isdisposed above the frame 5, and the control terminals 213 of thesemiconductor modules 21 are inserted and connected into the throughholes formed in the control circuit board 6. Subsequently, the circuitboard 6 is fixed to the board fixing sections 56 of the frame 5 by thescrews 561.

This completes assembly of the internal unit 10.

Thereafter, as shown in FIGS. 16 to 18, the internal unit 10 is fixed tothe case body 40.

More precisely, the unit fixing sections 51 of the frame 5 which servesas an outer shell of the internal unit 10 are placed on the uppersurfaces of the unit support sections 41 formed in the case body 40. Atthis time, the annular packings 333 attached to the coolant introductiontube 331 and the coolant discharge tube 332 are respectively fitted intothe concave portions 44 formed in the case body 40.

In this state, the bolts 511 are inserted into the thorough holes formedin the unit fixing sections 51, and screwed into the threaded holesformed in the unit support sections 41 in order to fix the internal unit10 to the case body 40.

Subsequently, as shown in FIGS. 1 and 19, the lid body 400 is placed onthe opening of the case body 40 with the seal member being interposedtherebetween, and the lid body 400 and the case body 40 are joinedtogether at their flange sections 42 and 420 by the bolts 431 and thenuts 432. As a result, the internal unit 10 is sealed in the case 4.

This completes assembly of the power conversion apparatus 1.

Note that the pressure member 12 may be disposed between the front endof the stacked body 11 and the front wall section 52.

In the following, the effects and advantages of this embodiment areexplained.

The power conversion apparatus 1 has the structure in which theelectronic components (the semiconductor modules 21, capacitor 22 and soon) and the cooler 3 are fixed to the frame 5, so that the electroniccomponents, the cooler 3 and the frame 5 are integrated as the internalunit 10. The internal unit 10 is fixed within the case 4. Accordingly,since the internal unit 10 serves as a beam of the case 4, the rigidityof the case 4 can be improved.

That is, since the case 4 can have a sufficient rigidity without beingincreased in the wall thickness, or being provided with reinforcingribs, it is possible to reduce the material cost and the manufacturingcost of the case 4, and also to reduce the weight of the case 4.

The two-layered structure of the case 4 and the frame 5 can effectivelyprevent the electronic components fixed to the frame 5 from being brokenby vibration of the vehicle. That is, due to the two-layered structure,the length of the internal unit 10 (distance between the unit fixingsections 51) is shorter than that of the case 4. Thus, the resonancefrequency of the internal unit 10 can be higher than that of the case 4.Consequently, compared with a case in which the electronic componentsare directly fixed to the case 4, the structure in which the electroniccomponents are fixed to the internal unit 10 can prevent the electroniccomponents from taking a load, thereby effectively preventing theelectronic components from being broken.

Fixing the internal unit 10 to the case 4 makes it possible to suppressexternal force applied to the respective electronic components and thecooler 3 included in the internal unit 10 through the case 4. This makesit possible to suppress the electronic components and the cooler 3included in the internal unit 10 from being affected by externalvibration and thermal stress.

The electronic components and other members are not directly fixed tothe case 4. The electronic components and the like are fixed to theframe 5, and the internal unit 10 is assembled. Thereafter, the internalunit 10 is fixed to the case 4, whereby the power conversion apparatus 1can be obtained. Accordingly, assembling work of the power conversionapparatus 1 becomes easy.

Also, maintenance of the power conversion apparatus 1 becomes easy,because the whole internal unit 10 can be removed from the case 4 formaintenance work.

Since assembly and maintenance of the power conversion apparatus 1 canbe carried out outside the case 4, the case 4 does not have to beprovided with two or more lids. Accordingly, the sealing surface betweenthe case body 40 and the lid body 400 can be one in number. This makesit possible to improve the water tightness of the case 4, and to reducethe sealing material of the case 4, to thereby reduce the material costand man-hour cost for application of the sealing material to the case 4.

The internal unit 10 is sealed in the case 4. That is, since the wholeinternal unit 10 including the frame 5 is sealed in the case 4, thesealing surface can be one in number.

Since the internal unit 10 is fixed to the frame 5 within the case 4,and the frame 5 serves as a beam of the case 4 as described above, therigidity of the case 4 can be further improved.

Since the frame 5 is made of a conductive material, and is shaped tosurround the semiconductor modules 21 from all four sides, it can shieldelectromagnetic noise emitted from the semiconductor modules 21. Thecase 4 is also made of a conductive material, and accordinglyelectromagnetic noise emitted from the semiconductor modules 21 can beshielded doubly by the frame 5 and the case 4. Since the frame 5 isshaped to surround the semiconductor modules 21 from the four sides,electromagnetic noise leaking from the power conversion apparatus 1 tothe four sides can be suppressed.

In addition, in the power conversion apparatus 1, the internal unit 10,in which the electronic components (the semiconductor modules 21,capacitor 22 and so on) and the cooler 3 are fixed to the frame 5, isfixed to the frame 5 within the case 4. Accordingly, when the unifiedfixing section (unit support section 41) is provided, and the outershape of the case 4 is changed depending on a mounting portion (enginecompartment or the like) for the power conversion apparatus 1, layoutinside the case 4 is not required to be changed depending on the vehicletype. Consequently, the power conversion apparatus can be applied to avariety of vehicle types without changing the structure of the internalunit 10 but by changing the layout of the case 4. Therefore theconversion apparatus 1 having high productivity can be obtained with lowmanufacturing cost.

As shown in FIGS. 7 and 10, the stacked body 11 in which the coolingtubes 31 and the semiconductor modules 21 are stacked alternately isincluded in the internal unit 10. Since this makes it possible toassemble the stacked body 11 outside the case 4, the power conversionapparatus 1 can be assembled more easily.

Since the stacked body 11 is constituted of the cooling tubes 31 and thesemiconductor modules 21 stacked alternately, the semiconductor modules21 can be cooled efficiently, and the stacked body 11 can be madecompact in size.

The internal unit 10 includes the pressure member 12. The pressuremember 12 is interposed between the rear wall section 53 of the frame 5and the rear end of the stacked body 11 whose front end is supported bythe front wall section 52 of the frame 5. Accordingly, the reactionforce of the pressure member 12 can be supported by the frame 5.Accordingly, the case 4 is not required to have rigidity large enough tobear the reaction force of the pressure member 12, to increase thethickness thereof, or to include ribs. This makes it possible to makethe case 4 light in weight and less expensive.

The frame 5 includes the four unit fixing sections 51, two of them beingdisposed on one side of the stacking direction X, the other two of thembeing disposed on the other side of the stacking direction X. These fourunit fixing sections 51 are located more outward in the stackingdirection X than the pair of support portions of the frame 5 (the innersurface 521 of the front wall section 52 and the inner surface 531 ofthe rear wall section 531) applied with the reaction force towardoutside in the stacking direction X from the stacked body 11 and thepressure member 12. Accordingly, the frame 5 can resist the reactionforce of the stacked body 11 and the pressure member 12 with the aid ofthe case 4. This is because the case 4 reinforces the frame 5, tothereby prevent the frame 5 from being deformed.

The frame 5 includes the front wall section 52, the rear wall section 53and the pair of side wall sections 54. Accordingly, the stacked body 11can be held stably within the frame 5.

The wall thicknesses of the front and rear wall sections 52 and 53 arelarger than those of the side wall sections 54. That is, as shown inFIGS. 4 and 5, the wall thickness t1 is larger than the wall thicknesst2. Accordingly, it is possible to improve the rigidities of the frontand rear wall sections 52 and 53 receiving the reaction force of thepressure member 12, while reducing the weight of the side wall sections54 not directly receiving the reaction force of the pressure member 12.This makes it possible to make the frame 5 light in weight effectively,while ensuring the frame 5 to have rigidity large enough to resist thereaction force of the pressure member 12.

As shown in FIG. 4, part of each of the front and rear wall sections 52is and 53 is constituted as the substantially H-shaped wall section 55.Accordingly, the frame 5 can be made light in weight, while ensuring thehigh rigidity of the front and rear wall sections 52 and 53.

As shown in FIG. 5, since each of the side wall sections 54 isconstituted as the substantially L-shaped wall section, it is possibleto reduce the weight of the side wall sections 54 and the material cost,while ensuring them to have sufficient rigidity.

As shown in FIG. 10, the semiconductor modules 21 stacked together withcooling tubes 31 have the structure in which the main electrodeterminals 212 and the control terminals 213 project toward the oppositesides in the height direction Z, and the frame 5 is open to both sidesin the height direction Z. Accordingly, as shown in FIGS. 8 and 13 to15, the bus bars 70 and 700 and the control circuit board 6 can beeasily fixed to the semiconductor modules 21.

The internal unit 10 includes also the control circuit board 6.Accordingly, since it is not necessary to fix the control circuit board6 directly to the case 4, the assembling work of the control circuitboard 6 can be facilitated, and external force applied to the controlcircuit boar 6 can be reduced.

As shown in FIG. 2, the unit fixing sections 51 provided in the frame 5are located outward of the outer edge of the control circuit board 6.Accordingly, the internal unit 10 can be easily fixed to the case 4.This is because if the unit fixing sections 51 are located inward of theouter edge of the control circuit board 6, the internal unit 10assembled with the control circuit board 6 cannot be easily fixed to thecase 4.

In this case, to fix the internal unit 10 to the case 4, it is necessaryto drill holes penetrating the wall of the case 4 through which bolts orthe like are inserted in, for example. However, in this case, not onlythe workability is lowered, but also more sealing members have to beused to ensure the water tightness of the case 4.

By locating the unit fixing sections 51 outward of the outer edge of thecontrol circuit board 6, such a problem can be removed.

The board fixing sections 56 of the frame 5 are located more inward thanthe unit fixing sections 51. This facilitates connecting the controlcircuit board 6 to the frame 5, and connecting the internal unit 10 tothe case 4.

The internal unit 10 includes also the capacitor 22. Accordingly, it ispossible to reduce external force applied to the capacitor 22. Further,it is possible to suppress vibration of the capacitor 22 beingtransmitted to the outside through the case 4. This makes it possible tosuppress unpleasant vibration noise from occurring in the vehicle cabinincorporating the power conversion apparatus 1 due to vibration of thecapacitor 22.

As shown in FIG. 3, the capacitor fixing sections 57 provided in theframe 5 are located more inward than the unit fixing sections 51.Accordingly, the capacitor 22 can be easily fixed to the frame 5, andthe internal unit 10 can be easily fixed to the case 4.

The internal unit 10 includes also the terminal block 7. Accordingly,since the terminal block 7 can be fixed to the internal unit 10 outsidethe case 4, the assembling work of the terminal block 7 can befacilitated.

The frame 5 includes the plurality of the bus bar fixing sections 58 forfixing the bus bars 70 and the bus bar assembly 72. Accordingly, the busbars 70 and the bus bar assembly 72 can be stably fixed to the frame 5.

As shown in FIGS. 3 and 8, two of the bus bar fixing sections 58 arelocated at the position closer to the terminal block 7 than to thecenter of the frame 5. Accordingly, the bus bar assembly 72 can bestably fixed to the frame 5, and the input/output terminals 71 can bestably disposed on the terminal block 7. As a result, a stableconnection between the input/output terminals 71 and external terminalscan be ensured.

The internal unit 10 includes all the electronic components constitutingthe power conversion circuit. Accordingly, all the electronic componentsconstituting the power conversion circuit can be protected from externalforce, and the power conversion apparatus easy to manufacture andexcellent in maintainability can be provided.

As described above, according to the first embodiment, a powerconversion apparatus can be provided which is capable of reducing anexternal force applied to its electronic components while improving therigidity of its case, and which is excellent in maintainability, can beeffectively mounted, and can be manufactured at low cost.

Second Embodiment

Next, the second embodiment is described with reference to FIGS. 20 to26. In the second embodiment, a wire holding section 59 for holding aconductive wire 15 is additionally provided in the frame 5 of the powerconversion apparatus 1.

At least one end of the conductive wire 15 is disposed within the case4. In this embodiment, the conductive wire 15 connects the capacitor 22with the control circuit board 6 within the case 4, so that the voltageacross the capacitor 22 can be sent to the control circuit board 6through the conductive wire 15 as a voltage signal indicative of theinput voltage of the power conversion apparatus 1.

The conductive wire 15 is covered with resin except both ends thereof,and has flexibility. The conductive wire 15 is laid outside the frame 5to make a connection between the control circuit board 6 and thecapacitor 22.

The wire holding section 59 has a hook-like shape when viewed from theheight direction Z as shown in FIGS. 21, 23, 25 and 26, and extends inthe height direction Z as shown in FIGS. 20, 22 and 24. The wire holdingsection 59 is formed in the front wall section 52 of the frame 5 so asto project outward therefrom. As shown in FIGS. 21 and 23, a part of theconductive wire 15 is fitted in the space between the wire holdingsection 59 and the front wall section 52.

As shown in FIGS. 20 to 23, the bus bar assembly 72 is formed with aforward projecting section 721 projecting forward in the stackingdirection X. The forward projecting section 721 is located in a positionopposite to the open side of the wire holding section 59 when viewedfrom the height direction Z. The forward projecting section 721 servesto prevent the conductive wire 15 from coming off the wire holdingsection 59.

The wire holding section 59 is located at substantially the sameposition in the lateral direction Y as a connector section 151 of theconductive wire 15 for connection with the control circuit board 6.

The components of this embodiment are the same as those of the firstembodiment except for the above.

In the second embodiment, the conductive wire 15 can be laid along theframe 5. Accordingly, the internal unit 10 can be prevented from beingcaught by the conductive wire 15 when it is put in or taken out of thecase 4.

Other than the above, the second embodiment provides the same advantagesas those provided by the first embodiment.

It is possible that the wire holding section 59 holds a wire differentfrom the conductive wire 15 provided for making a connection between thecapacitor 22 and the control circuit board 6. The wire holding section59 may be formed in a shape and a position different from thosedescribed above, so that the conductive wire 15 can be laid along thelateral direction Y. The wire holding section 59 may be formed in two ormore positions in the frame 5.

Third Embodiment

Next, the third embodiment is described with reference to FIGS. 27 to29. In the power conversion apparatus 1 of the third embodiment, theunit fixing sections 51 of the frame 5 project outward in the stackingdirection X from the front wall section 52 and the rear wall section 53.

In this embodiment, as shown in FIG. 27, four unit fixing sections 51diagonally project outward from four corners of the frame 5, and oneunit fixing section 51 projects forward from the front wall section 52,when viewed from the height direction Z. That is, the unit fixingsections 51 provided at the four corners of the frame 5 project outwardin the stacking direction X from the front wall section 52 and the rearwall section 53, and project outward in the lateral direction Y from thepair of side wall sections 54. The unit fixing section 51 provided onthe front wall section 52 is disposed between the pair of concaveportions 522 provided in the front wall section 52, that is, between thecoolant introduction tube 331 and the coolant discharge tube 332.

The rear wall section 53 has concave portions 532, which are recessedinward, at the both ends thereof.

The rear wall section 53 is provided with board fixing sections 56,which are component fixing sections, at the outside in the stackingdirection X of the concave portions 532.

In this embodiment, the wall thicknesses of the front wall section 52and the rear wall section 53 are larger than the wall thicknesses of theside wall sections 54. In addition, a part of each of the front wallsection 52 and the rear wall section 53 forms the H-shaped wall section55 as in the case of the first embodiment (refer to FIGS. 2 and 4). Notethat, as shown in FIG. 29, in each of the H-shaped wall sections 55, oneor more ribs 553, which are orthogonal to the plate sections 551 and theconnecting section 552, are partially provided between the pair of platesections 551 and the connecting section 552.

At least a part of each of the side wall sections 54 forms an L-shapedwall section as in the case of the first embodiment (refer to FIGS. 2and 5).

As shown in FIG. 27, a pair of support pins 14, which support thepressure member 12, is held between both ends 121 of the pressure member12 and the rear wall section 53. The support pins 14 contact the rearwall section 53 at the positions closer to the side wall sections 54than to the H-shaped wall section 55 provided on the rear wall section53. Specifically, the H-shaped wall section 55 are provided so that theH-shaped wall section 55 does not exist at positions to which thesupport pins 14 are projected in the stacking direction X.

The rear wall section 53 is constituted of a pair of pin supports 533,which contact the support pins 14, the H-shaped wall section 55, whichis formed between the pair of pin supports 533, and concave formedportions 534 formed between the pair of pin supports 533 and the sidewall sections 54. The concave portions 532 are formed in the concaveformed portions 534. The board fixing sections 56 project over theconcave formed portions 534 in the height direction Z.

The wall thicknesses of the pin supports 533 are larger than that of theH-shaped wall section 55 of the rear wall section 53. The pin supports533 project inward and outward in the stacking direction X with respectto the H-shaped wall section 55.

The H-shaped wall section 55 of the rear wall section 53 is providedwith the rib 553 at the center thereof in the longitudinal direction(lateral direction Y).

The concave portions 532 are opposed to edges 122 of the both ends 121of the pressure member 12 which are located at the outside in thelateral direction Y of the portions which are supported by the supportpins 14

The front wall section 52 has the pair of concave portions 522 at bothoutsides in the lateral direction Y of the H-shaped wall section 55. Thecoolant introduction tube 331 and the coolant discharge tube 332 of thecooler 3 are respectively disposed in the concave portions 522. Thefront wall section 52 has the pair of board fixing sections 56, whichproject in the height direction Z, at the inside of the pair of concaveportions 522 and the outside of the H-shaped wall section 55. Clampfixing sections 523 to which damping members (not shown) are fixed arerespectively formed at the outsides of the concave portions 522. Theclamping members respectively clamp the coolant introduction tube 331and the coolant discharge tube 332.

The H-shaped wall section 55 of the front wall section 52 has the ribs553 at two positions in the lateral direction Y. The H-shaped wallsection 55 of the front wall section 52 project forward in the stackingdirection X.

The components of this embodiment are the same as those of the firstembodiment except for the above.

According to this embodiment, the strength of the frame 5 for resistingthe reaction force of the pressure member 12 can be effectivelyincreased without increasing the frame 5 in size and weight. The rearwall section 53 of the frame 5 receives the reaction force of thepressure member 12. Hence, the wall thickness of the rear wall section53 is increased to improve the rigidity thereof, thereby reliablypreventing the frame 5 from being deformed by the reaction force of thepressure member 12. If the thicknesses of all parts of the frame 5 areincreased, the frame 5 increases in size and weight. Since the wallthicknesses of the side wall sections 54, which do not directly receivethe reaction force of the pressure member 12, can be relatively small,the wall thickness of the rear wall section 53 can be larger than thoseof the side wall sections 54. Hence, the strength of the frame 5 forresisting the reaction force of the pressure member 12 can beeffectively increased without increasing the frame 5 in size and weight.Note that the above advantages can be obtained from the power conversionapparatus 1 of the first embodiment.

The unit fixing sections 51 respectively project outward from the frontwall section 52 and the rear wall section 53 in the stacking directionX. Hence, the strength of the frame 5 in the stacking direction X can beeffectively increased. That is, by forming the unit fixing sections 51so as to respectively project from the front wall section 52 and therear wall section 53, the frame 5 is reinforced in the stackingdirection X by the case 4. Consequently, the strength of the frame 5 forresisting the reaction force of the pressure member 12 can be increasedby effective reinforcement by the case 4.

Since the rear wall section 53 has the concave portions 532, as shown inFIG. 28, the pressure member 12 can be easily pushed in the stackingdirection X at the edges 122 thereof by using pressure jigs J. That is,spaces, in which the pressure jigs 3 are set which are used forelastically deforming the pressure member 12, can be ensured as theconcave portions 532.

Following is a procedure for disposing the pressure member 12 at aposition between the stacked body 11 and the rear wall section 53 sothat the pressure member 12 pushes the stacked body 11 (shown in FIG.27). First, the stacked body 11 and the pressure member 12, which is ina free state (the state before elastically deformed), are disposed inthe frame 5. Next, the pressure jigs J are disposed in the frame 5 so asto contact the both edges 122 of the pressure member 12 in the stackingdirection X from the back side. Next, while fixing the pressure member12, the pressure jigs 3 are moved forward, thereby elastically deformingthe pressure member 12. Thereafter, the support pins 14 are interposedbetween the both ends 121 of the pressure member 12 and the rear wallsection 53. Next, the pressure jigs J are gradually returned backward,whereby the support pins 14 are held between the both ends 121 of thepressure member 12 and the rear wall section 53. Accordingly, thepressure member 12 is kept in a state where the pressure member 12 iselastically deformed with the predetermined amount of displacement andis pushed in the stacking direction X by the predetermined amount ofpressure.

As described above, when the pressure jigs J are disposed between thepressure member 12 and the rear wall section 53 in the frame 5 toelastically deform the pressure member 12, spaces are required in whichthe pressure jigs are to be disposed. Since the pressure jigs J arerequired to provide large pressing force, the pressure jigs J are largein size to some extent. Hence, the spaces in which the pressure jigs Jare disposed can be ensured in the frame 5 by providing the concaveportions 532.

The rear wall section 53 is provided with the unit fixing sections 51and the board fixing sections 56 at outside positions in the stackingdirection X of the portions where the concave portions 532 are formed.Thus, the strength of the portions (concave formed portions 534), wherethe concave portions 532 of the rear wall section 53 are formed, can beprevented from lowering. That is, when the concave portions 532 areprovided, the wall thickness of the rear waif section 53 becomespartially small, whereby the strength thereof can be lowered. However,by disposing the board fixing sections 56 on the thinned portions, theboard fixing sections 56 serve as reinforcing members, therebypreventing the strength of the rear wall section 53 from lowering.

The thickness of the front wall section 52 is larger than thethicknesses of the side wall sections 54. Since the thickness of thefront wall section 52, which receives the reaction force of the pressuremember 12 through the stacked body 11, is large, the strength of theframe 5 can be effectively increased.

At least parts of the front wall section 52 and the rear wall section 53are formed with the H-shaped wall sections 55 which include the ribs553. Hence, the rigidity of the H-shaped wall sections 55 can be furtherimproved. Specifically, the ribs 553 formed along the direction in whichthe reaction force of the pressure member 12 is applied can increase thestrength of the H-shaped wall sections 55 for resisting the reactionforce of the pressure member 12.

The pair of support pins 14 contact the rear wall section 53 at thepositions closer to the side wall sections 54 than to the H-shaped wallsection 55 provided on the rear wall section 53. This makes it possibleto make the rear wall section 53 light in weight, while preventing therear wall section 53 from being deformed. Since the H-shaped wallsection 55 is formed with less material, the weight of the H-shaped wallsection 55 can be reduced, whereas the strength of the H-shaped wallsection 55 becomes relatively low. The portions of the rear wall section53 which the support pins 14 contact take a heavy load. Hence, when suchportions are provided on the H-shaped wall section 55, the frame iseasily deformed. To solve the problem, by making the support pins 14contact the rear wall section 53 at the positions closer to the sidewall sections 54 than to the H-shaped wall section 55, the frame 5 canbe light in weight, while the frame 5 can be reliably prevented frombeing deformed.

Other than the above, the third embodiment provides the same advantagesas those provided by the first embodiment.

In the above embodiments, the cooler is constituted as the stacked bodyof the cooling tubes and the semiconductor modules. However, the presentinvention is also applicable to a power conversion apparatus including acooling structure in which a semiconductor element, a metal bodythermally coupled to this semiconductor element and a sealing member areintegrated as a sealed semiconductor-integrated cooling structure havinga coolant channel allowing coolant to flow toward the metal body, and aplurality of such sealed semiconductor-integrated cooling structures arestacked such that the sealed semiconductor-integrated cooling structuresand coolant passages alternate in the stacking direction.

In the above embodiments, the pressure member is disposed between thereal wall section and the rear end of the stacked body. However, thepressure member may be disposed between the front wall section and thefront end of the stacked body. In this case, when the coolantintroduction tube and the coolant discharge tube are disposed side byside protruding from the front wall section, the pressure member may bedisposed between the front wall section (first wall section) and thefront end of the stacked body so as to be located between the coolantintroduction tube and the coolant discharge tube, and the stacked bodymay be supported by the rear wall section (second wall section). In thiscase, the “front wall section (first wall section)” corresponds to “rearwall section” in claims, and the “rear wall section (second wallsection)” corresponds to “front wall section” in the claims.

Hereinafter, aspects of the above-described embodiments will besummarized.

As an aspect of the embodiment, a power conversion apparatus includes:electronic components configuring a power conversion circuit; a coolerfor cooling at least part of the electronic components; and a casehousing the electronic components and the cooler; wherein the at leastpart of the electronic components and the cooler are fixed to andintegrated in a frame as an internal unit, the internal unit is fixedwithin the case through the frame, and the frame has such a shape thatthe at least part of the electronic components is surrounded by theframe from four sides.

The power conversion apparatus has the structure in which at least partof the electronic components and the cooler are fixed to the frame, sothat the electronic components, the cooler and the frame are integratedas the internal unit. The internal unit is fixed within the case.Accordingly, since the internal unit serves as a beam of the case, therigidity of the case can be improved.

That is, since the case can have a sufficient rigidity without beingincreased in the wall thickness, or being provided with reinforcingribs, it is possible to reduce the material cost and the manufacturingcost of the case, and also to reduce the weight of the case.

Fixing the internal unit to the case makes it possible to suppressexternal force applied to the respective electronic components and thecooler included in the internal unit through the case. This makes itpossible to suppress the electronic components and the cooler includedin the internal unit from being affected by external vibration andthermal stress.

The electronic components and other members are not directly fixed tothe case. The electronic components and the like are fixed to the frame,and the internal unit is assembled. Thereafter, the internal unit isfixed to the case, whereby the power conversion apparatus can beobtained. Accordingly, assembling work of the power conversion apparatus1 becomes easy.

Also, maintenance of the power conversion apparatus becomes easy,because the whole internal unit can be removed from the case formaintenance work.

Since assembly and maintenance of the power conversion apparatus can becarried out outside the case, the case does not have to be provided withtwo or more lids. Accordingly, the sealing surface between the case bodyand the lid body can be one in number. This makes it possible to improvethe water tightness of the case, and to reduce the sealing material ofthe case, to thereby reduce the material cost and man-hour cost forapplication of the sealing material to the case.

Since the internal unit is fixed to the frame within the case, and theframe serves as a beam of the case as described above, the rigidity ofthe case can be further improved.

The frame has such a shape that at least, part of the electroniccomponents configuring the internal unit is surrounded by the frame fromfour sides. Hence, when the frame is made of a conductive material, itcan shield electromagnetic noise emitted from the semiconductor modules.The case is often made of a conductive material, and accordinglyelectromagnetic noise emitted from the semiconductor modules can beshielded doubly by the frame and the case. In addition, the frame hassuch a shape that the at least part of the electronic componentsconfiguring the internal unit is surrounded by the frame from foursides. Hence, when the frame surrounds the electronic components, suchas the semiconductor modules, which are liable to emit electromagneticnoise, and the frame is a conductor, electromagnetic noise leaking to atleast the four sides surrounded by the frame can be suppressed.

In addition, in the power conversion apparatus, the internal unit, inwhich the electronic components and the cooler are fixed to the frame,is fixed to the frame within the case. Accordingly, when the unifiedfixing section is provided, and the outer shape of the case is changeddepending on a mounting portion (engine compartment or the like) for thepower conversion apparatus, layout inside the case is not required to bechanged depending on the vehicle type. Consequently, the powerconversion apparatus can be applied to a variety of vehicle typeswithout changing the structure of the internal unit but by changing thelayout of the case. Therefore the conversion apparatus having highproductivity can be obtained with low manufacturing cost.

As described above, a power conversion apparatus can be provided whichis capable of reducing an external force applied to its electroniccomponents while improving the rigidity of its case, and which isexcellent in maintainability and can be manufactured at low cost.

The power conversion apparatus according to the embodiment is installedin an electric vehicle, a hybrid vehicle or the like, and is used toconvert source power into driving power for a drive motor.

In the power conversion apparatus, preferably, the internal unitincludes semiconductor modules, which incorporate switching elements, asthe electronic components, the cooler includes coolant passages, theinternal unit incorporates a stacked body in which the coolant passagesand the semiconductor modules are stacked alternately, the internal unitincludes a pressure member for pressing the stacked body in the stackingdirection, the frame includes a front wall section and a rear wallsection located on both sides in the stacking direction of the stackedbody, and a pair of side wall sections joining the front and rear wallsections at both ends thereof, the pressure member is interposed betweenthe rear wall section and a rear end in the stacked direction of thestacked body whose front end in the stacked direction is supported bythe front wall section, and the thickness of the rear wall section islarger than the thicknesses of the side wall sections.

In this case, the strength of the frame for resisting the reaction forceof the pressure member can be effectively increased without increasingthe frame in size and weight. The rear wall section of the framereceives the reaction force of the pressure member. Hence, the wallthickness of the rear wall section is increased to improve the rigiditythereof, thereby reliably preventing the frame from being deformed bythe reaction force of the pressure member. If the thicknesses of allparts of the frame are increased, the frame increases in size andweight. Since the wall thicknesses of the side wall sections, which donot directly receive the reaction force of the pressure member, can berelatively small, the wall thickness of the rear wall section can belarger than those of the side wall sections. Hence, the strength of theframe for resisting the reaction force of the pressure member can beeffectively increased without increasing the frame in size and weight.

Note that the above power conversion apparatus differs from a generalpower conversion apparatus in which electronic components are mounted ona flat supporting member. The above power conversion apparatus includesa stacked body in which the coolant passages and the semiconductormodules are stacked alternately.

In the power conversion apparatus, the coolant passages are preferablyformed by cooling tubes.

In the power conversion apparatus, the frame preferably includes unitfixing sections for fixing the internal unit to the case, and the unitfixing sections project to the outside of the frame.

In this case, the strength of the frame can be easily ensured withoutincreasing the frame in size. If the unit fixing sections are providedon wall sections of the frame such as the front wall section, the rearwall section and the side wall sections, the wall sections are requiredto be provided with concave portions, whereby the strength of the framecan be lowered. If the unit fixing sections are provided inside theframe, the wall sections of the frame shift outward, thereby increasingthe frame in size. Hence, by making the unit fixing sections project tothe outside of the frame, the strength of the frame can be ensuredwithout increasing the frame in size.

In the power conversion apparatus, at least parts of the unit fixingsections preferably project outward in the stacking direction from thefront wall section and the rear wall section.

In this case, the strength of the frame in the stacking direction can beeffectively increased. That is, by forming the unit fixing sections soas to respectively project from the front wall section and the rear wallsection, the frame is reinforced in the stacking direction by the case.

Consequently, the strength of the frame for resisting the reaction forceof the pressure member can be increased by effective reinforcement bythe case.

In the power conversion apparatus, the rear wall section preferably hasconcave portions, which are recessed inward, at both ends thereof.

In this case, the pressure member can be easily pushed in the stackingdirection at edges thereof by using pressure jigs. That is, spaces, inwhich the pressure jigs are disposed which are used for elasticallydeforming the pressure member, can be ensured as the concave portions.

In the power conversion apparatus, the rear wall section preferablyincludes at least one of a unit fixing section for fixing the internalunit to the case, and a component fixing section for fixing theelectronic components, at the outside in the stacking direction of theconcave portion.

In this case, the strength of the portions, where the concave portionsof the rear wall section are formed, can be prevented from lowering.That is, when the concave portions are provided, the wall thickness ofthe rear wall section becomes partially small, whereby the strengththereof can be lowered. However, by disposing the unit fixing section orthe component fixing section on the thinned portion, the unit fixingsection or the component fixing section serves as a reinforcing member,thereby preventing the strength of the rear wall section from lowering.

In the power conversion apparatus thicknesses of the front wall sectionand the rear wall section are preferably larger than thicknesses of theside wall sections.

In this case, since the thickness of the front wall section, whichreceives the reaction force of the pressure member through the stackedbody, is large, the strength of the frame can be effectively increased.

In the power conversion apparatus, at least part of at least one of thefront wall section and the rear wall section is preferably formed withan H-shaped wall section having a substantially H-shaped cross section,the H-shaped wall section including a pair of plate sectionsperpendicular to the stacking direction, and a connecting sectionconnecting the pair of plate sections together at the center of the pairof plate sections.

In this case, the frame can be made light in weight, while ensuring highrigidity of at least one of the front wall section and the rear wallsection.

In the power conversion apparatus, in the H-shaped wall section, a riborthogonal to the plate sections and the connecting section ispreferably partially provided between the plate sections and theconnecting section.

In this case, the rigidity of the H-shaped wall sections can be furtherimproved. Specifically, the ribs formed along the direction in which thereaction force of the pressure member is applied can increase thestrength of the H-shaped wall sections for resisting the reaction forceof the pressure member.

In the power conversion apparatus, preferably, the rear wall sectionincludes the H-shaped wall section, a pair of support sections, whichsupport the pressure member, are held between both sides of the pressuremember and the rear wall section, and the support sections contact therear wall section at a position closer to the side wall section than tothe H-shaped wall section.

In this case, the rear wall section can be made light in weight, whilepreventing the rear wall section from being deformed. Since the H-shapedwall section is formed with less material, the weight of the H-shapedwall section can be reduced, whereas the strength of the H-shaped wallsection becomes relatively low. The portions of the rear wall sectionwhich the support sections contact take a heavy load. Hence, when suchportions are provided on the H-shaped wall section, the frame is easilydeformed. To solve the problem, by making the support sections contactthe rear wall section at the positions closer to the side wall sectionsthan to the H-shaped wall section, the frame can be light in weight,while the frame can be reliably prevented from being deformed.

In the power conversion apparatus, at least a part of the side wallsection is preferably formed with an L-shaped wall section having asubstantially L-shaped cross section, the L-shaped wall sectionincluding a main wall portion having a major surface facing an innerside of the frame, and an inward portion projecting toward the innerside of the frame from one end of the main wall portion in the directionperpendicular to the stacking direction.

In this case, the side wall section can be made light in weight, and thematerial cost of the side wall section can be reduce, while ensuringsufficient rigidity thereof.

In the power conversion apparatus, preferably, the cooling tubes havelong-length (elongated) shapes, and are connected to each other in thevicinity of both ends in the longitudinal directions thereof, thesemiconductor modules stacked together with the cooling tubes have thestructure in which a main electrode terminal performing input and outputof controlled electric power and a control terminal performing input ofa control current for controlling the switching elements project towardopposite sides and project in the height direction orthogonal to thestacking direction and the longitudinal directions of the cooling tubes,and the frame is open to both sides in the height direction, andincludes a to board fixing section for fixing a control circuit board,to which the control terminal is connected, and a bus bar fixing sectionfor fixing a bus bar, to which the main electrode terminal is connected,at opposite sides in the height direction.

In this case, the frame can be fixed without interference between thecontrol circuit board and the bus bar. Since the layout in which theinterference between the control circuit board and the bus bar can beavoided is not required, the space can be saved. Since the controlcircuit board, which is a weak current component, and the bus bar, whichis a strong current component, are disposed at opposite sides with theframe therebetween, the effect of electromagnetic noise to the controlcircuit board can be suppressed.

In addition, since the board fixing section and the bus bar fixingsection are disposed at positions in the height direction of the frame,the strength of the frame for resisting the reaction force, which theframe receives from the stacked body and the pressure member, can beincreased by the control circuit board and the bus bar.

In the power conversion apparatus, the frame preferably includes acapacitor fixing section for fixing a capacitor at the side in theheight direction at which the bus bar fixing section is located.

In this case, since the capacitor, which is a weak current component,can be disposed at a position opposite to the control circuit board withthe frame therebetween, the effect of electromagnetic noise to thecontrol circuit board can be suppressed. In addition, since thecapacitor fixing sections are disposed at positions in the heightdirection of the frame, the effect can be further suppressed.

In the power conversion apparatus, the internal unit is preferablysealed within the case.

In this case, water penetration to the internal unit can be prevented.Since the entire internal unit, including the frame, is sealed in thecase, the sealing surface of the case body can be one in number. Hence,water tightness of the case can he improved, sealing material of thecase can be reduced, and the material cost and man-hour cost forapplication of the sealing material to the case can be reduced.

In the power conversion apparatus, the frame is preferably made ofconductive material.

In this case, the frame can shield electromagnetic noise emitted fromthe semiconductor modules. The case is often made of a conductivematerial, and accordingly electromagnetic noise emitted from thesemiconductor modules can be shielded doubly by the frame and the case.In addition, the frame has such a shape that the at least part of theelectronic components configuring the internal unit is surrounded by theframe from four sides. Hence, when the frame surrounds the electroniccomponents, such as the semiconductor modules, which are liable to emitelectromagnetic noise, electromagnetic noise leaking from at least thefour sides surrounded by the frame can be suppressed.

The internal unit preferably includes the semiconductor modules, whichincorporate switching elements, as the electronic components. In thiscase, an external force applied to the semiconductor modulesincorporating the switching elements, which are liable to be affected bythe external force, can be reduced. Hence, durability of the powerconversion apparatus can be effectively improved.

Preferably, the cooler includes cooling tubes each having therein acoolant passage, and the internal unit incorporates therein a stackedbody in which the cooling tubes and the semiconductor modules arestacked alternately. Since this makes it possible to assemble thestacked body outside the case, the power conversion apparatus can beassembled more easily.

The stacked body is preferably configured with the cooling tubes and thesemiconductor modules stacked alternately. In this case, thesemiconductor modules can be cooled efficiently, and the stacked bodycan be made compact in size.

The internal unit preferably includes a pressure member for pressing thestacked body in the stacking direction. The pressure member ispreferably interposed between a part of the frame and one end of thestacked body in the stacking direction. The stacked body is preferablysupported by another part of the frame at the other end thereof in thestacking direction. In this case, the reaction force of the pressuremember can be supported by the frame. Accordingly, the case is notrequired to have rigidity large enough to bear the reaction force of thepressure member, to increase the thickness thereof, or to include ribs.This makes it possible to make the case light in weight and lessexpensive.

The frame preferably includes unit fixing sections for fixing theinternal unit to the case. At least one unit fixing section ispreferably located on the outside of each of a pair of support sectionsin the stacking direction at which the frame is applied with thereaction force toward the outside in the stacking direction applied fromthe stacked body and the pressure member. In this case, the frame canresist the reaction force of the stacked body and the pressure memberwith the aid of the case. This is because the case reinforces the frame,to thereby effectively prevent the frame from being deformed.

The frame preferably includes a front wall section and a rear wallsection located on both sides of the stacked body in the stackingdirection, and a pair of side wall sections joining the front and rearwall sections at both ends thereof. In this case, the stacked body canbe held stably within the frame.

Thicknesses of the front wall section and the rear wall section arepreferably larger than those of the side wall sections. In this case, itis possible to improve the rigidities of the front and rear wallsections receiving the reaction force of the pressure member, whilereducing the weight of the side wall sections not directly receiving thereaction force of the pressure member. This makes it possible to makethe frame light in weight effectively, while ensuring the frame to haverigidity large enough to resist the reaction force of the pressuremember.

At least part of the front wall section and the rear wall sectionpreferably forms an H-shaped wall section having a substantiallyH-shaped cross section, the H-shaped wall section being configured witha pair of longitudinal plate sections perpendicular to the stackingdirection, and a connecting section connecting the pair of longitudinalplate sections together at the center of the pair of longitudinal platesections. In this case, the frame can be made light in weight, whileensuring the high rigidity of the front and rear wall sections.

Preferably, the cooling tubes have long-length shapes, and are connectedto each other in the vicinity of both ends in the longitudinaldirections thereof. Preferably, the semiconductor modules stackedtogether with the cooling tubes have the structure in which the mainelectrode terminals performing input/output of controlled electric powerand the control terminals performing input of a control current forcontrolling the switching elements project toward the opposite sides andproject in the height direction orthogonal to the stacking direction andthe longitudinal directions of the cooling tubes. The frame ispreferably open to both sides in the height direction. In this case, thebus bars, the control circuit board and the like can be easily fixed tothe semiconductor modules.

The internal unit preferably includes a control circuit board on which acontrol circuit for controlling the switching elements is formed. Inthis case, since it is not necessary to fix the control circuit boarddirectly to the case, the assembling work of the control circuit boardcan be facilitated, and external force applied to the control circuitboard can be reduced.

Preferably, the frame includes unit fixing sections for fixing theinternal unit to the case, and the unit fixing sections are located moreoutward than the outer edge of the control circuit board. In this case,the internal unit can be easily fixed to the case. This is because ifthe unit fixing sections are located inward of the outer edge of thecontrol circuit board, the internal unit assembled with the controlcircuit board cannot be easily fixed to the case. In this case, to fixthe internal unit to the case, it is necessary to drill holespenetrating the wall of the case through which bolts or the like areinserted in, for example. However, in this case, not only theworkability is lowered, but also more sealing members have to be used toensure the water tightness of the case. By locating the unit fixingsections outward of the outer edge of the control circuit board, such aproblem can be removed.

Preferably, the frame is provided with board fixing sections for fixingthe control circuit board to the internal unit, and the board fixingsections are located more inward than the unit fixing sections. Thisfacilitates connecting the control circuit board to the frame, andconnecting the internal unit to the case.

The internal unit preferably includes a capacitor as the electroniccomponent.

In this case, it is possible to reduce external force applied to thecapacitor. Further, it is possible to suppress vibration of thecapacitor being transmitted to the outside through the case. This makesit possible to suppress unpleasant vibration noise from occurring in thevehicle cabin incorporating the power conversion apparatus due tovibration of the capacitor.

Preferably, the frame includes the unit fixing sections for fixing theinternal unit to the case and the capacitor fixing sections for fixingthe capacitor to the internal unit. The capacitor fixing sections arepreferably located more inward than the unit fixing sections. In thiscase, the capacitor can be easily fixed to the frame, and the internalunit can be easily fixed to the case.

The internal unit preferably includes a terminal block on whichinput/output terminals for input and output of controlled electric powerare mounted for making connection between the input/output terminals andterminals of external devices. In this case, since the terminal blockcan be fixed to the internal unit outside the case, the terminal blockcan be easily fixed.

Preferably, the power conversion apparatus includes bus bars providedwith the input/output terminals at one ends thereof, and the frameincludes the plurality of the bus bar fixing sections for fixing the busbars. In this case, the bus bars can be stably fixed to the frame.

The power conversion apparatus preferably includes a plurality of busbars at least two of which configures an integrated bus bar assembly bybeing partially molded with resin. At least two of the bus bar fixingsections, which fix the bus bar assembly to the frame, are preferablylocated at the position closer to the terminal block than to the centerof the frame. In this case, the bus bar assembly can be stably fixed tothe frame, and the input/output terminals can be stably disposed on theterminal block. As a result, a stable connection between theinput/output terminals and external terminals can be ensured.

The internal unit preferably includes all the electronic componentsconfiguring the power conversion circuit. In this case, all theelectronic components configuring the power conversion circuit can beprotected from an external force, and the power conversion apparatuseasy to manufacture and excellent in maintainability can be provided.

The frame preferably includes a wire holding section for holding aconductive wire whose at least one end is disposed within the case. Inthis case, the conductive wire can be laid along the frame. Accordingly,the internal unit can be prevented from being caught by the conductivewire when it is put in or taken out of the case.

It will be appreciated that the present invention is not limited to theconfigurations described above, but any and all modifications,variations or equivalents, which may occur to those who are skilled inthe art, should be considered to fall within the scope of the presentinvention.

1. A power conversion apparatus comprising: electronic components configuring a power conversion circuit; a cooler for cooling at least part of the electronic components; and a case housing the electronic components and the cooler; wherein the at least part of the electronic components and the cooler are fixed to and integrated in a frame as an internal unit, the internal unit is fixed within the case through the frame, and the frame has such a shape that the at least part of the electronic components is surrounded by the frame from four sides.
 2. The power conversion apparatus according to claim 1, wherein the internal unit includes semiconductor modules, which incorporate switching elements, as the electronic components, the cooler includes coolant passages, the internal unit incorporates a stacked body in which the coolant passages and the semiconductor modules are stacked alternately, the internal unit includes a pressure member for pressing the stacked body in the stacking direction, the frame includes a front wall section and a rear wall section located on both sides in the stacking direction of the stacked body, and a pair of side wall sections joining the front and rear wall sections at both ends thereof, the pressure member is interposed between the rear wall section and a rear end in the stacked direction of the stacked body whose front end in the stacked direction is supported by the front wall section, and the thickness of the rear wall section is larger than the thicknesses of the side wall sections.
 3. The power conversion apparatus according to claim 1, wherein the coolant passages are formed by cooling tubes.
 4. The power conversion apparatus according to claim 3, wherein the frame includes unit fixing sections for fixing the internal unit to the case, and the unit fixing sections project to the outside of the frame.
 5. The power conversion apparatus according to claim 4, wherein at least parts of the unit fixing sections project outward in the stacking direction from the front wall section and the rear wall section.
 6. The power conversion apparatus according to claim 3, wherein the rear wall section has concave portions, which are recessed inward, at both ends thereof.
 7. The power conversion apparatus according to claim 6, wherein the rear wall section includes at least one of a unit fixing section for fixing the internal unit to the case, and a component fixing section for fixing the electronic components, at the outside in the stacking direction of the concave portion.
 8. The power conversion apparatus according to claim 3, wherein thicknesses of the front wall section and the rear wall section are larger than thicknesses of the side wall sections.
 9. The power conversion apparatus according to claim 8, wherein at least part of at least one of the front wall section and the rear wall section is formed with an H-shaped wall section having a substantially H-shaped cross section, the H-shaped wall section including a pair of plate sections perpendicular to the stacking direction, and a connecting section connecting the pair of plate sections together at the center of the pair of plate sections.
 10. The power conversion apparatus according to claim 9, wherein in the H-shaped wall section, a rib orthogonal to the plate sections and the connecting section is partially provided between the plate sections and the connecting section.
 11. The power conversion apparatus according to claim 3, wherein the rear wall section includes the H-shaped wall section, a pair of support sections, which support the pressure member, are held between both sides of the pressure member and the rear wall section, and the support sections contact the rear wall section at a position closer to the side wall section than to the H-shaped wall section.
 12. The power conversion apparatus according to claim 3, wherein at least a part of the side wall section is formed with an L-shaped wall section having a substantially L-shaped cross section, the L-shaped wall section including a main wall portion having a major surface facing an inner side of the frame, and an inward portion projecting toward the inner side of the frame from one end of the main wall portion in the direction perpendicular to the stacking direction.
 13. The power conversion apparatus according to claim 3, wherein the cooling tubes have long-length shapes, and are connected to each other in the vicinity of both ends in the longitudinal directions thereof, the semiconductor modules stacked together with the cooling tubes have the structure in which a main electrode terminal performing input and output of controlled electric power and a control terminal performing input of a control current for controlling the switching elements project toward opposite sides and project in the height direction orthogonal to the stacking direction and the longitudinal directions of the cooling tubes, and the frame is open to both sides in the height direction, and includes a board fixing section for fixing a control circuit board, to which the control terminal is connected, and a bus bar fixing section for fixing a bus bar, to which the main electrode terminal is connected, at opposite sides in the height direction.
 14. The power conversion apparatus according to claim 13, wherein the frame includes a capacitor fixing section for fixing a capacitor at the side in the height direction at which the bus bar fixing section is located.
 15. The power conversion apparatus according to claim 1, wherein the internal unit is sealed within the case.
 16. The power conversion apparatus according to claim 1, wherein the frame is made of conductive material. 